When a lens is mounted on the camera it will be at maximum aperture (f/2.8). It stops down to the selected aperture when the photo is taken (or the DOF preview is pressed). With a manual lens you can only shoot in 'A' (aperture priority), or 'M' modes, and you must select the aperture using the aperture ring on the lens, the camera cannot select the aperture.

It depends on what you mean by "manual lens". Most people mean manual focus lenses. Manual focus lenses can either be chipped or not chipped. A chipped lens will allow the aperture to be controlled by the camera, you do not have to use the aperture ring. You can choose whether to use the aperture ring or the camera command dial by a setting in the custom menus.

Most of the new Samyang / Rokinon lenses for Nikon mount coming out these days have a CPU chip in them and can have the aperture controlled by the camera (set aperture ring to f/22) or by the aperture ring.

The exposures indicated by the camera in the two cases seem correct. That is to say, if the camera said f/2.8 at 1/25s and the exposure came out correct then f/22 at 3s seems like the correct reading. So the most obvious question then becomes "did the aperture blades close when you pressed the shutter?" This is easy enough to test. Simply set the lens to f/22 and look into the lens when you press the shutter. It should be easy to see the aperture blades close.

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Mike Dawson

My lenses are not chipped, probably because it's the Cine versions. Which would explain then why I have not been able to control aperture on the camera.

I did a quick test to see if I can see the aperture blades close when I press the shutter. Nope... looks like it stays open at its widest at F2.8 and F1.4 on my 35mm.

I really believe something has changed. It's like the lens stays open at F1.4, even when the camera the aperture ring is set at F22. So the camera thinks I'm taking a photo at F22 when in actual fact it stays at its widest aperture, which is why my images are over exposed. Like I said, it hasn't done this before.

I just remembered something else. In video mode, even while recording I used to be able to control aperture with the lens.

The day after I got the camera I made this video, the very first video I have done with it, and here you can see very well at around 35 secs when I turned the aperture ring: